Reinforced plastic containers

ABSTRACT

A plastic container that may be used in hot fill applications includes a finish portion having an opening, a main body portion and a bottom portion. The main body portion includes a vacuum panel area and a circumferentially extending reinforcement groove that has reinforcement structure provided therein positioned substantially adjacent to the vacuum panel area. The bottom portion includes a standing ring, a central interior substantially flat portion that has a plurality of alternating parallel ribs and grooves defined therein and a transitional surface between the standing ring and the substantially flat portion. The parallel ribs and grooves define a complex structure with respect to the transitional surface that provides a stiffening effect, particularly in containers that are fabricated from polypropylene.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of plastic containers, and more particularly to plastic containers that require reinforcement against deflection as a result of internal volumetric changes or the weight of the contents of the container.

2. Description of the Related Technology

Plastic containers such as those that are manufactured using the extrusion blow molding process need to possess the requisite strength to limit sidewall and bottom deflection to stay within predetermined tolerances in response to forces that are applied during the filling process and during handling within the supply chain and by the consumer. Hot fill type plastic containers typically include vacuum panel areas having vacuum panels specifically designed to accommodate deflection as a result of the volumetric expansion and contraction that occurs during the filling process. However, it is desirable to minimize deflection in sidewall and bottom portion areas of a hot fill container other than in the vacuum panels in order to preserve the structural integrity of the container.

The bottom portion of a plastic container also needs to process sufficient strength to resist deformation as a result of pressurization changes within the container and from the forces that are applied by the weight of the container contents. In hot fill type containers, it is also important for the bottom portion to have sufficient rigidity so that vacuum uptake is directed mainly to the vacuum panels that are designed for such purposes.

In certain types of plastic containers, such as those that are manufactured using the stretch reheat blow molding process, a certain amount of reinforcement is inherently provided by the concave shape of the bottom portion. Concavity can also be designed into the bottom portion of an extrusion blow molded plastic container, but this sacrifices space efficiency and increases material costs. The extrusion blow molding process permits the fabrication of the container that has a substantially flat bottom. Extrusion blow molded containers that have a substantially rectangular profile when viewed in transverse cross-section have been manufactured with corrugated substantially flat bottoms for use in limiting the deflection of the bottom of the container as a result of the weight of solid materials within the container. However, to the inventor's knowledge no such bottoms have been used when the container that is substantially round when viewed in transverse cross-section, or in hot fill applications.

A need exists to provide a plastic container that effectively directs vacuum uptake to the intended portions of the container, and that limits deflection of the bottom portion as a result of pressurization changes within the container and the weight of the container contents.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a plastic container that effectively directs vacuum uptake to the intended portions of the container, and that limits deflection of the bottom portion as a result of pressurization changes within the container and the weight of the container contents.

In order to achieve the above and other objects of the invention, a hot fill type plastic container according to a first aspect of the invention includes a finish portion defining an opening, a bottom portion and a main body portion having a vacuum panel area with at least one vacuum panel defined therein. The vacuum panel is constructed and arranged to deflect in order to accommodate volumetric expansion and contraction during the hot fill process. The main body portion further includes a circumferentially extending reinforcement groove having reinforcement structure provided therein. The circumferentially extending reinforcement groove is positioned substantially adjacent to the vacuum panel area, whereby dimensional distortion of at least part of the main body portion that is adjacent to the vacuum panel area is minimized during hot fill process.

A hot fill type plastic container according to a second aspect of the invention includes a finish portion defining an opening, a bottom portion that is substantially round when viewed in bottom plan and a main body portion having a vacuum panel area with at least one vacuum panel defined therein. The vacuum panel is constructed and arranged to deflect in order to accommodate volumetric expansion and contraction during the hot fill process. The bottom portion is constructed and arranged to include a substantially flat portion having a plurality of alternating parallel ribs and grooves defined therein. As a result, dimensional distortion of the bottom portion is minimized during the hot fill process and deflection as a result of vacuum uptake is directed toward the vacuum panel area.

A polypropylene container according to a third aspect of the invention includes a finish portion defining an opening, a main body portion having a vacuum panel area defined therein and a bottom portion that is fabricated from polypropylene and that is substantially round when viewed in bottom plan. The bottom portion is constructed and arranged to include a substantially flat portion having a plurality of alternating parallel ribs and grooves defined therein. As a result, dimensional distortion of the bottom portion is minimized.

These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a first perspective view of a plastic container that is constructed according to a preferred embodiment of the invention;

FIG. 2 is a side elevational view of the plastic container that is shown in FIG. 1,

FIG. 3 is a longitudinal cross-sectional view taken along lines 3-3 in FIG. 1;

FIG. 4 is a transverse cross-sectional view taken along lines 4-4 in FIG. 2;

FIG. 5 is a transverse cross-sectional view taken along lines 5-5 in FIG. 2;

FIG. 6 is a second side elevational view of the plastic container that is shown in FIG. 1;

FIG. 7 is a fragmentary cross-sectional view taken along lines 7-7 in FIG. 6;

FIG. 8 is a rear elevational view of the container that is depicted in FIG. 1;

FIG. 9 is a front elevational view of the container that is depicted in FIG. 1;

FIG. 10 is a top plan view of the container that is depicted in FIG. 1;

FIG. 11 is a bottom plan view of the container that is depicted in FIG. 1;

FIG. 12 is a cross-sectional view taken along lines 12-12 and FIG. 11;

FIG. 13 is a bottom perspective view of the container that is depicted in FIG. 1;

FIG. 14 is a finite element analysis image comparison illustrating the top load performance benefits of the container that is constructed according to the preferred embodiment of the invention;

FIG. 15 is a graph depicting the improvement in top load performance that is exhibited by a container that is constructed according to the preferred embodiment of the invention; and

FIG. 16 is a table comparison demonstrating the improvement in bottom deflection performance in a container that is constructed according to the preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to FIG. 1, a plastic container 10 that is constructed according to a preferred embodiment of the invention is preferably fabricated from polypropylene using a conventional extrusion blow molding process. Plastic container 10 in the preferred embodiment is designed for use with a conventional hot fill process. Plastic container 10 includes a finish portion 12 that defines an opening 14 that is in communication with the interior of the container 10. Plastic container 10 further includes a bottom portion 16, which will be described in greater detail below.

Plastic container 10 also includes a main body portion 18 having a vacuum panel area 20, each of which includes a vacuum panel 22 having inner portion 24 and an outer portion 26. The vacuum panel area 20 is preferably recessed with respect to an outer sidewall 28 of the main body portion 18. As FIG. 5 shows, the outer portions 26 of the vacuum panels 22 are substantially flat and substantially perpendicular to a radius extending from a longitudinal axis 25 of the container 10. The inner portions 24 of the vacuum panels 22 are constructed so as to be slightly convex and are designed to flex inwardly when an under pressure exists within the container 10 during the hot fill process.

The vacuum panel area 20 further includes transition portions 30 that connect the outer portions 26 of the vacuum panels 22 to the outer sidewall 28 of the main body portion 18.

Plastic container 10 further includes a dome or shoulder portion 32 that connects the finish portion 12 to the main body portion 18. In the preferred embodiment, the dome portion 32 is provided with a handle 38 that is constructed and arranged to facilitate a single finger grip.

Container 10 is preferably a round container, meaning that its outermost surfaces as viewed in transverse cross-section are substantially circular. This may best be seen in FIGS. 4 and 5.

The main body portion 18 further preferably includes a circumferentially extending reinforcement groove 34 that has reinforcement structure 36 provided therein. The reinforcement groove 34 imparts additional top load strength of the container 10, as well as hoop strength, meaning that it stabilizes adjacent portions of the sidewall of the container 10 against radial displacement as a result of internal pressurization changes and squeezing forces that may be applied to the container 10 during handling or by a consumer.

The circumferentially extending reinforcement groove 34 is preferably shaped and proportioned the same as those that are disclosed in U.S. patent application Ser. No. 13/348,249, filed May 30, 2012, the entire disclosure of which is hereby incorporated by reference as if set forth fully herein.

The reinforcement groove 34 is preferably positioned substantially adjacent to the vacuum panel area 20 in order to minimize dimensional distortion of the sidewall of the main body portion 18 adjacent to the vacuum panel area 20 during the hot fill process. Preferably, the reinforcement groove 34 is positioned within a distance L1 of the vacuum panel area 20 that is substantially no greater than about 34 millimeters, more preferably substantially no greater than about 22 millimeters and most preferably substantially no greater than about 14 millimeters.

In the preferred embodiment, the reinforcement groove 34 includes a plurality of flutes 40 that are situated within the groove 34. Each of the flutes 40 preferably has a vertical component, and more preferably is oriented so as to be substantially vertical. The reinforcement groove 34 preferably extends about an entire circumference of the main body portion 18.

As FIG. 4 shows, the flutes 40 are preferably defined by alternating convex outer surfaces 43 and concave surfaces 42. The main body portion 18 has a maximum lateral dimension W_(MAX), as is also shown in FIG. 4. The reinforcement groove 34 has a minimum depth D_(MIN) and a maximum depth D_(MAX) as measured from the outer sidewall 28, with a minimum depth D_(MIN) being defined at the peaks of the convex surfaces 43 and the maximum depth D_(MAX) being defined at the radially innermost points of the concave troughs that are formed by the concave surfaces 42.

Preferably, a ratio D_(MIN)/D_(MAX) of the minimum depth of the maximum depth is substantially within a range of about 0.1 to about 0.9, more preferably substantially within a range of about 0.2 to about 0.8 and most preferably substantially within a range of about 0.35 to about 0.65.

As FIG. 7 shows, the circumferentially extending reinforcement groove 34 as viewed in side profile or longitudinal cross-section has a first upper groove sidewall 47 that is angled with respect to a groove bottom 48 at a first angle and a second lower groove sidewall 49 that is angled with respect to the groove bottom 48 that a second angle. In the preferred embodiment, the first and second angles are preferably substantially the same. In addition, the first upper groove sidewall 47 defines a wedge angle A₁ with respect to the second lower groove sidewall 49 that is preferably substantially within a range of about 15° to about 45° and more preferably substantially within a range of about 20° to about 40°.

The presence of the circumferentially extending reinforcement groove 34 materially improves both the top load and pressure resistance performance of the container in comparison to a similar container that does not include such a reinforcement groove 34. FIG. 14 is a finite element analysis comparison depicting the relative deflections under a top load force between a container, shown on the left, which does not include a reinforcement groove 34 and the container that is constructed according to the preferred embodiment, which is shown on the right. The darker coloration of the container that is shown on the right is representative of a lessened amount of deflection relative to the container on the left.

FIG. 15 is a graphical depiction of the relative top load performance of the containers shown on the left and right, respectively, in FIG. 14. The horizontal axis in FIG. 15 represents displacement, while the vertical axis represents a top load force that is applied to the container. The container that is shown on the left in FIG. 14, which does not include a profiled reinforcement groove 34, as indicated as the “original structure” in FIG. 15. The container that is shown on the right in FIG. 14 is constructed according to the preferred embodiment of the invention and does include a reinforcement groove 34, is indicated as the “final structure” in FIG. 15. As FIG. 15 shows, a significant improvement in top load performance is achieved by the inclusion of the profiled reinforcement groove 34.

Referring now to FIGS. 11 and 13, it will be seen that the bottom portion 16 is constructed and arranged to include a substantially flat portion 52 that has a plurality of alternating ribs 56 and grooves 58 defined therein. The presence of the alternating ribs and grooves 56, 58 minimize dimensional distortion of the bottom portion 16 during the hot fill process and direct deflection as a result of vacuum uptake to portions of the container 10 that are designed to accommodate such uptake, namely the vacuum panel area 20.

Bottom portion 16 further includes a standing ring 50 that in the preferred embodiment extends continuously about an outer periphery of the bottom portion 16 as viewed in bottom plan. The substantially flat portion 52 is preferably positioned within the standing ring 50 and is substantially centered with respect to the standing ring 50. The substantially flat portion 52 moreover preferably occupies at least 75% of the space that is defined within the standing ring 50. A transitional surface 54 is preferably defined between the substantially flat portion 52 and the standing ring 50. The transitional surface 54 is also preferably shaped so as to be substantially symmetrical about the longitudinal axis 25 of the container 10.

As FIG. 11 shows, the alternating parallel ribs and grooves 56, 58 intersect the transitional surface 54 to form a complex shape that stiffens the bottom portion against deformation. The complex shape is particularly effective in stiffening the bottom portion when the bottom portion 16 is fabricated from polypropylene, as a result of the characteristic material properties of polypropylene.

FIG. 16 is a table comparison showing the improved performance of the bottom portion 16 of the container 10 that is constructed according to the preferred embodiment of the invention relative to a similar predecessor container that does not have the alternating parallel ribs and grooves 56, 58. The table on the left in FIG. 16 depicts the base deflection at various points on the container bottom on the predecessor container. The table on the right in FIG. 16 depicts the base deflection at analogous points in a container 10 that is constructed according to the preferred embodiment of the invention. The diminution in deflection and resulting enhanced dimensional stability of the bottom portion and a container that is constructed according to a preferred embodiment of the invention is evident from the data that is provided in FIG. 16.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. An extrusion blow-molded hot fill type plastic container, comprising: a finish portion defining an opening; a bottom portion; a main body portion having a vacuum panel area with at least one vacuum panel defined therein and arranged to accommodate volumetric expansion and contraction, wherein the main body portion further includes a circumferentially extending reinforcement groove having reinforcement structure provided therein, and wherein the circumferentially extending reinforcement groove is positioned substantially adjacent to the vacuum panel area, wherein the reinforcement structure comprises a plurality of flutes within the circumferentially extending reinforcement groove, the plurality of flutes including alternating convex and concave surfaces defining a generally sinusoidal pattern in plan view, whereby dimensional distortion of at least part of the main body portion that is adjacent to the vacuum panel area is minimized during hot fill process.
 2. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein the bottom portion is constructed and arranged so as to be substantially flat with a plurality of alternating parallel ribs and grooves defined therein, whereby dimensional distortion of the bottom portion is minimized during the hot fill process and deflection as a result of vacuum uptake is directed toward the vacuum panel area.
 3. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein each of the plurality of flutes has a vertical component.
 4. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein each of the flutes is oriented so as to be substantially vertical.
 5. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein the circumferentially extending reinforcement groove extends about an entire circumference of the main body portion.
 6. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein the circumferentially extending reinforcement groove has a minimum depth and a maximum depth, and wherein a ratio of the minimum depth to the maximum depth is substantially within a range of about 0.1 to about 0.9.
 7. The extrusion blow-molded hot fill type plastic container according to claim 6, wherein the ratio of the minimum depth to the maximum depth is substantially within a range of about 0.2 to about 0.8.
 8. The extrusion blow-molded hot fill type container according to claim 7, wherein the ratio of the minimum depth to the maximum depth is substantially within a range of about 0.35 to about 0.65.
 9. The extrusion blow-molded hot fill type container according to claim 1, wherein the circumferentially extending reinforcement groove as viewed in longitudinal cross-section has a first upper groove sidewall that is angled with respect to a groove bottom at a first angle and a second lower groove sidewall that together with the upper groove sidewall defines a wedge that is angled with respect to the groove bottom at a wedge angle that is substantially within a range of about 15° to about 45°.
 10. The extrusion blow-molded hot fill type plastic container according to claim 9, wherein the wedge angle is substantially within a range of about 20° to about 40°.
 11. An extrusion blow-molded hot fill type plastic container, comprising: a finish portion defining an opening; a bottom portion that is substantially round when viewed in bottom plan view; a main body portion having a vacuum panel area with at least one vacuum panel defined therein and arranged to accommodate volumetric expansion and contraction, the main body portion further including a circumferentially extending reinforcement groove having reinforcement structure provided therein, the reinforcement structure comprising a plurality of flutes within the circumferentially extending reinforcement groove, the plurality of flutes including alternating convex and concave surfaces defining a generally sinusoidal pattern in plan view; wherein the bottom portion is constructed and arranged to include a substantially flat portion having a plurality of alternating parallel ribs and grooves defined therein, whereby dimensional distortion of the bottom portion is minimized during hot fill process and deflection as a result of vacuum uptake is directed toward the vacuum panel area.
 12. The extrusion blow-molded hot fill type plastic container according to claim 11, wherein the bottom portion further includes a standing ring, and the substantially flat portion is positioned within the standing ring and elevated with respect to the standing ring.
 13. The extrusion blow-molded hot fill type plastic container according to claim 12, wherein the substantially flat portion is substantially centered with respect to the standing ring.
 14. The extrusion blow-molded hot fill type plastic container according to claim 12, wherein the substantially flat portion occupies at least 75% of an area defined within the standing ring.
 15. The extrusion blow-molded hot fill type plastic container according to claim 12, further comprising a transitional surface between the substantially flat portion and the standing ring, and wherein the alternating parallel ribs and grooves of the substantially flat portion intersect the transitional surface to form a complex shape that stiffens the bottom portion against deformation.
 16. The extrusion blow-molded hot fill type plastic container according to claim 15, wherein the transitional surface is shaped so as to be substantially symmetrical about a longitudinal axis of the hot fill type plastic container.
 17. The extrusion blow-molded hot fill type plastic container according to claim 15, wherein the bottom portion is fabricated from a material comprising polypropylene.
 18. An extrusion blow-molded polypropylene container, comprising: a finish portion defining an opening; a main body portion having a vacuum panel area defined therein, the main body portion further including a circumferentially extending reinforcement groove having reinforcement structure provided therein, the reinforcement structure comprising a plurality of flutes situated within the circumferentially extending reinforcement groove, the plurality of flutes including alternating convex and concave surfaces defining a generally sinusoidal pattern in plan view; and a bottom portion fabricated from polypropylene and substantially round when viewed in bottom plan view, the bottom portion including a substantially flat portion having a plurality of alternating parallel ribs and grooves defined therein, whereby dimensional distortion of the bottom portion is minimized.
 19. The extrusion blow-molded polypropylene container according to claim 18, wherein the bottom portion further includes a standing ring, and the substantially flat portion is positioned within the standing ring and elevated with respect to the standing ring.
 20. The extrusion blow-molded polypropylene container according to claim 19, wherein the substantially flat portion is substantially centered with respect to the standing ring.
 21. The extrusion blow-molded polypropylene container according to claim 19, wherein the substantially flat portion occupies at least 75% of that is an area defined within the standing ring.
 22. The extrusion blow-molded polypropylene container according to claim 19, further comprising a transitional surface between the substantially flat portion and the standing ring, and wherein the alternating parallel ribs and grooves of the substantially flat portion intersect the transitional surface to form a complex shape that stiffens the bottom portion against deformation.
 23. The extrusion blow-molded polypropylene container according to claim 22, wherein the transitional surface is shaped so as to be substantially symmetrical about a longitudinal axis of the container.
 24. The extrusion blow-molded hot fill type plastic container according to claim 1, wherein the circumferentially extending reinforcement groove is positioned on the main body portion between the finish portion and the vacuum panel area.
 25. The extrusion blow-molded hot fill type plastic container according to claim 24, wherein the circumferentially extending reinforcement groove is positioned no more than 34 millimeters from the vacuum panel area. 